import math
import torch
import torch.nn as nn
import torch.nn.functional as F
from ..module.nonlocal_block import NONLocalBlock2D
from ..module.scse import SCSE_Block
from ..module.attention import AttentionLayer
from ..module.mish import Mish


class BasicBlock(nn.Module):
    def __init__(self, in_planes, out_planes, stride, dropRate=0.0):
        super(BasicBlock, self).__init__()
        self.bn1 = nn.BatchNorm2d(in_planes)
        self.relu1 = Mish()
        # self.relu1 = nn.ReLU(inplace=True)
        self.conv1 = nn.Conv2d(in_planes, out_planes, kernel_size=3, stride=stride,
                               padding=1, bias=False)
        self.bn2 = nn.BatchNorm2d(out_planes)
        self.relu2 = Mish()
        # self.relu2 = nn.ReLU(inplace=True)
        self.conv2 = nn.Conv2d(out_planes, out_planes, kernel_size=3, stride=1,
                               padding=1, bias=False)
        self.droprate = dropRate
        self.equalInOut = (in_planes == out_planes)
        self.convShortcut = (not self.equalInOut) and nn.Conv2d(in_planes, out_planes, kernel_size=1, stride=stride,
                               padding=0, bias=False) or None
    def forward(self, x):
        if not self.equalInOut:
            x = self.relu1(self.bn1(x))
        else:
            out = self.relu1(self.bn1(x))
        out = self.relu2(self.bn2(self.conv1(out if self.equalInOut else x)))
        if self.droprate > 0:
            out = F.dropout(out, p=self.droprate, training=self.training)
        out = self.conv2(out)
        return torch.add(x if self.equalInOut else self.convShortcut(x), out)

class NetworkBlock(nn.Module):
    def __init__(self, nb_layers, in_planes, out_planes, block, stride, dropRate=0.0):
        super(NetworkBlock, self).__init__()
        self.layer = self._make_layer(block, in_planes, out_planes, nb_layers, stride, dropRate)
    def _make_layer(self, block, in_planes, out_planes, nb_layers, stride, dropRate):
        layers = []
        for i in range(int(nb_layers)):
            layers.append(block(i == 0 and in_planes or out_planes, out_planes, i == 0 and stride or 1, dropRate))
        return nn.Sequential(*layers)
    def forward(self, x):
        return self.layer(x)

class WideResNet(nn.Module):
    def __init__(self, depth, num_classes, widen_factor=1, dropRate=0.0, nonlocal_block=False, scse_block=False, attention_block=False):
        super(WideResNet, self).__init__()
        nChannels = [16, 16*widen_factor, 32*widen_factor, 64*widen_factor]
        assert((depth - 4) % 6 == 0)
        n = (depth - 4) / 6
        block = BasicBlock
        # 1st conv before any network block
        self.conv1 = nn.Conv2d(3, nChannels[0], kernel_size=3, stride=1,
                               padding=1, bias=False)
        self.nonlocal_block = nonlocal_block
        self.scse_block = scse_block
        self.attention_block = attention_block
        if nonlocal_block:
            self.nonlocal_block1 = NONLocalBlock2D(nChannels[0], sub_sample=True, bn_layer=True)
        if scse_block:
            self.scse_block1 = SCSE_Block(nChannels[0])

        # 1st block
        self.block1 = NetworkBlock(n, nChannels[0], nChannels[1], block, 1, dropRate)
        if nonlocal_block:
            self.nonlocal_block2 = NONLocalBlock2D(nChannels[1], sub_sample=True, bn_layer=True)
        if scse_block:
            self.scse_block2 = SCSE_Block(nChannels[1])
        if attention_block:
            self.attention2 = AttentionLayer(nChannels[1], 16)
        # 2nd block
        self.block2 = NetworkBlock(n, nChannels[1], nChannels[2], block, 2, dropRate)
        if nonlocal_block:
            self.nonlocal_block3 = NONLocalBlock2D(nChannels[2], sub_sample=True, bn_layer=True)
        if scse_block:
            self.scse_block3 = SCSE_Block(nChannels[2])
        if attention_block:
            self.attention3 = AttentionLayer(nChannels[2], 32)
        # 3rd block
        self.block3 = NetworkBlock(n, nChannels[2], nChannels[3], block, 2, dropRate)

        # global average pooling and classifier
        self.bn1 = nn.BatchNorm2d(nChannels[3])
        # self.relu = nn.ReLU(inplace=True)
        self.relu = Mish()
        self.fc = nn.Linear(nChannels[3], num_classes)
        self.nChannels = nChannels[3]

        for m in self.modules():
            if isinstance(m, nn.Conv2d):
                nn.init.kaiming_normal_(m.weight, mode='fan_out', nonlinearity='relu')
            elif isinstance(m, nn.BatchNorm2d):
                m.weight.data.fill_(1)
                m.bias.data.zero_()
            elif isinstance(m, nn.Linear):
                m.bias.data.zero_()
    def forward_features(self, x, pool=False):
        out = self.conv1(x)
        if self.nonlocal_block:
            out = self.nonlocal_block1(out)
        if self.scse_block:
            out = self.scse_block1(out)

        out = self.block1(out)
        if self.nonlocal_block:
            out = self.nonlocal_block2(out)
        if self.scse_block:
            out = self.scse_block2(out)
        if self.attention_block:
            out = self.attention2(out)
        out = self.block2(out)
        if self.nonlocal_block:
            out = self.nonlocal_block3(out)
        if self.scse_block:
            out = self.scse_block3(out)
        if self.attention_block:
            out = self.attention3(out)
        out = self.block3(out)

        out = self.relu(self.bn1(out))
        return out

    def forward(self, x):
        out = self.conv1(x)
        out = self.block1(out)
        out = self.block2(out)
        out = self.block3(out)
        out = self.relu(self.bn1(out))
        out = F.avg_pool2d(out, 8)
        out = out.view(-1, self.nChannels)
        return self.fc(out)